THE GREAT FAULT TROUGHS OF THE ANTILLES 93 



pletely submerge the floor of the trough and separate the Tiburon 

 Peninsula from the rest of Haiti. 



The depression has been described and figured by Jones as a 

 normally faulted block, buried under Quaternary deposits which 

 have been removed at one place exposing highly tilted Oligocene- 

 Miocene sediments. Limestones of Eocene-Early OHogcene age 

 are exposed along the flanks of the inclosing ranges while late 

 Tertiary intrusives form the core of the mountains on the south. 

 Another "large fault is indicated well up on the south range of 

 Haiti, a well-marked depression extending east and west along the 

 course of this fault. "^ 



Along the north side of the salt lakes Jones found basalt-flows, 

 which he thinks came from fissure eruptions; and he states that 

 between the Cul-de-Sac depression and Ville Bonheur (Saut d' Eau) 

 there is a well-defined crater from which extend basalt-flows, 

 so recent in origin that they have not been appreciably modified 

 by erosion.^ In the Province of Azua, Santo Domingo, there are 

 rocks of igneous origin, which C. W. Cooke states are not older than 

 Pleistocene.^ 



During historic times the fault trough of southern Haiti has 

 been the locus of more earthquakes of high intensity than any similar 

 area in the Greater Antilles. The high seismicity of this depression 

 is noted by Scherer in his excellent article on "Great Earthquakes 

 in the Island of Haiti "^ from which most of the data on Haitian 

 earthquakes given in this paper have been abstracted. 



The cities of Azua and Santo Domingo, located on alluvial 

 ground a short distance north of the fault zone and near its juncture 

 with the Caribbean escarpment, have been damaged repeatedly 

 by earthquakes. They suffered from severe shocks in 1673, 1684, 

 and 1691, Azua being entirely destroyed in 1691. On October 

 18, 1 75 1, an earthquake threw down all houses in Azua and a 

 sea-wave overwhelmed the town. It was rebuilt farther inland. 



^ Ibid., p. 751. ' Ibid., pp. 750-51. 



sC. W. Cooke, "Geological Reconnaissance in Santo Domingo," Bull. Geol^ 

 Soc. Amer., Vol. XXXI (1920), p. 218. 



4 Rev. J. Scherer, " Great Earthquakes in the Island of Haiti, " Bull. Seis. Soc. 

 Amer., Vol. II (1912), pp. 161-80. 



